SPIGOT-1068: Limit the number of patterns on banners

nms-patches/TileEntityBanner.patch

@@ -0,0 +1,26 @@
+--- a/net/minecraft/server/TileEntityBanner.java
++++ b/net/minecraft/server/TileEntityBanner.java
+@@ -20,6 +20,11 @@
+ 
+             if (nbttagcompound.hasKey("Patterns")) {
+                 this.patterns = (NBTTagList) nbttagcompound.getList("Patterns", 10).clone();
++                // CraftBukkit start
++                while (this.patterns.size() > 20) {
++                    this.patterns.a(20); // PAIL Rename remove
++                }
++                // CraftBukkit end
+             }
+ 
+             if (nbttagcompound.hasKeyOfType("Base", 99)) {
+@@ -54,6 +59,11 @@
+         super.a(nbttagcompound);
+         this.color = nbttagcompound.getInt("Base");
+         this.patterns = nbttagcompound.getList("Patterns", 10);
++        // CraftBukkit start
++        while (this.patterns.size() > 20) {
++            this.patterns.a(20); // PAIL Rename remove
++        }
++        // CraftBukkit end
+         this.h = null;
+         this.i = null;
+         this.j = null;

src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaBanner.java

@@ -50,8 +50,8 @@ public class CraftMetaBanner extends CraftMetaItem implements BannerMeta {
 
         if (entityTag.hasKey(PATTERNS.NBT)) {
             NBTTagList patterns = entityTag.getList(PATTERNS.NBT, 10);
-            for (int i = 0; i < patterns.size(); i++) {
-                NBTTagCompound p = (NBTTagCompound) patterns.get(i);
+            for (int i = 0; i < Math.min(patterns.size(), 20); i++) {
+                NBTTagCompound p = patterns.get(i);
                 this.patterns.add(new Pattern(DyeColor.getByDyeData((byte) p.getInt(COLOR.NBT)), PatternType.getByIdentifier(p.getString(PATTERN.NBT))));
             }
         }